Anglian Water’s £3 million investment to protect and improve water quality at Watton Water Recycling Centre and meet Water Framework Directive targets in Norfolk is being delivered with a sand filtration technology solution from Hydro International.

The Hydro International solution includes the supply of six DynaSand® Oxy vertical sand filters which have been designed to optimise ammonia removal from treated effluent discharge. The filters will also form part of an important Environment Agency (EA) national trial into more effective reduction of total phosphorus content from treated waste waters.

Hydro International has worked closely with Anglian Water’s project team to develop a detailed design solution for the site as part of the plant upgrade. The wastewater treatment plant serves the rural Norfolk town of Watton and outlying villages. In a rich farming area, with relatively low rainfall and slow river flow, there are particular challenges to keep pollutants such as ammonia and phosphorus out of the biosphere.  

 Bill Measham, Project Delivery Manager, WRNI (Water Recycling Non Infrastructure) for Anglian Water explained: 

“Watton WRC has been identified by the Environment Agency under “no deterioration”. This means that to prevent its discharge consent status deteriorating, additional measures are needed to address ammonia levels in order to sufficiently treat all required flow, meet discharge consents and maintain the quality of receiving water bodies.”

 “Anglian Water is also taking part in a national Environment Agency phosphorus removal trial and we are working with Hydro International to use the new DynaSand® filters in a year-long optimisation trial with the very low target of 0.1mg/l of total phosphorus.”

 The trials follow on from successful work between Anglian and Hydro International with DynaSand filtration technology at Stalham sewage treatment works to reduce phosphate discharges on the Norfolk broads.

 Paul Barter, Principal Process Engineer for Hydro International’s European Wastewater Division said: 

“We are delighted to be working with Anglian Water on this innovative project. DynaSand® Oxy provides proven and effective technology for ammonia removal and at the same time, the DynaSand® filter action is excellent for removal of fine suspended solids as part of tertiary polishing of final discharges. Introducing ferric sulphate solution to the effluent enables phosphate to be rapidly converted into solids that can be easily removed by the DynaSand® filter.”

Bill Measham added:

“The current practice at Watton is to inject ferric salts after the primary treatment. This enables the works to average comfortably under the 1.0 mg/l consent. The inflow to the new DynaSand® Oxy filters will be from the secondary humus tank. We will be adding ferric salts at this point to see how low we can get the total phosphorus content and after the year’s trial, the plant will revert to the current level of treatment, but we should have much data on the performance of this promising solution.”

Hydro International project teams are supporting the design, installation and full commissioning of the filters.  Other plant improvements include inlet screen replacements and new hydraulic equipment.